I don't think human heads (what with their FaceGen geometry) would be all that easy to do. Creature heads, on the other hand, are certainly possible, and this is a wonderful idea.
No? I thought for certain there would be ways to do this.
I mean, they've created utilities that allow the player to take the face from one character and put it onto another in a completely different game. Obviously, the game must store this information somewhere.
Surely there could be a way, maybe with NVSE, to make human heads work...
Maybe not, though... I don't know.
I'm not the modeler sort. I'm an interiors guy, mostly. Dialogue, too, once I learn how to do it again.